XML and embedded systems

[James Spink <jimspink@hotmail.com>]

(long note warning)

I’m a newbie to the XML world.  I have a problem I’m hoping others may have 
seen and may have suggestions on:

I have an embedded system that I’ll need to communicate data to and from a 
client.  Generally, the client will make a request and the server will 
respond, i.e. with data, success/failure, etc.

In  particular, the client will need to be able to get and set some 
parameters on the system.  Some of the items are fairly complicated 
structures or lists, while others are simple strings.  The list of items 
that the system needs configuration for will vary based upon what the device 
is installed into.  In addition, over time, the device may evolve additional 
function requiring new or changed parameters.   The connection to it will be 
TCP/IP but of limited bandwidth and only directly to/from the client.

This system will have a JVM and HTTP server available.  Adding something 
like Java servlet capabilities is a possibility.  XML came to mind as a way 
to communicate this data since its flexible, has rich toolsets available in 
multiple languages, and can communicate data layout as a part of the 
payload.   It could even be used to have the device tell what items it 
supports and how.  This device doesn’t necessarily have to present an HTML 
interface for configuration, though it could.  There will be two principal 
clients – the manufacturer of this device (who wants to set it up in 
quantity) and the service center that uses this device (who wants to 
periodically change some device parameters on individual devices).  Both of 
these environments place a higher value on a client-side programmatic 
interface rather than a user interface as they usually wish to minimize user 
typing when dealing with the device.  The client could for example generate 
and consume the XML directly, or use supplied libraries to produce/consume 
the XML.

Has anyone dealt with this before?  My current thinking is to keep it simple 
and use my own XML grammar – XML at its simplest, so to speak.  One way I 
thought of would be to transmit the XML via HTTP by using a POST transaction 
and placing the entity in the HTTP message body, then respond with XML.  Or 
I could do something simpler and simply send an XML-encoded request over a 
socket and respond using XML.

I’ve looked at some of the many technologies invented for XML, but most of 
them seem like overkill for this scenario.  There aren’t databases involved, 
nor is this going to be an Internet application.

Comments?

Thanks!
Jim Spink

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